This invention relates in general to sun screens for absorbing a portion of the light entering an automobile window and more specifically, to a system for automatically moving a sun screen to cover automobile windows of trapezoidal or other non-rectangular shapes.
Since the earliest days of automobiles, discomfort and danger have been the lot of drivers driving towards a low, rising or setting, sun. Passengers also find the sun shining in through a side or rear window uncomfortable. Most automobiles include two hinged sun visors adjacent to the windshield which can be swung down over the upper part of the windshield and sometimes swung to the side to cover a portion of the front side windows. While better than nothing, these sun visors often have insufficient size or movability to intercept light from a very low sun. Since they absolutely block the passage of light, they can obstruct a driver's vision to the extent that other vehicles or the like are not seen.
In an attempt to overcome some of these problems with sun visors, sometimes windows are completely coated with a film of light absorbing material. However, since these sun screens cannot be removed, they are ordinarily illegal for use on windshields and front side windows, because the light absorbing characteristics are undesirable and dangerous at night or in low light conditions.
Attempts have been made to provide moveable sun screens which can be stowed away from the window and deployed over the window as conditions require. A number of mechanically complex window curtain raising and lowering systems were devised in the early days of automobiles, such as those disclosed by Ames in U.S. Pat. No. 1,798,577, Blancanrd in U.S. Pat. No. 1,977,844 and Courtwright in U.S. Pat. No. 2,023,666. Generally, these were intended to move a covering over a window opening and were only useful with rectangular openings.
Later, window shades of the type usually used in homes, having a shade wrapped roller with an internal torsion spring, so the shade could be deployed by pulling it down an latching it and stowed by releasing the latch and allowing the torsion spring to rewind the shade were applied to automobiles. Typical of these systems is that described by Merkl in U.S. Pat. No. 1,973,382 for use with the rear window of an automobile. Again, these were only suitable for use with rectangular windows, since otherwise considerable distracting light will leak around the shade edges.
More recently, a complex horizontally moveable light-blocking shade arrangement has been disclosed by Worrall in U.S. Pat. No. 4,874,026. This system, however, is intended only for use when the vehicle is parked to prevent sun damage to upholstery and the like. This system also is not readily useful with non-rectangular windows.
A window shade for use in the highly-sloped rear windows of modern automobiles is described by Woodworth in U.S. Pat. No. 4,898,224. A shade would on a roller is positioned below the window with a central pulley arrangement extending up over the center of the widow to pull the shade upwardly and forwardly along the window. This system does not seem adaptable to windshields because of the central deployment mechanism which would block a central area of the driver's forward view and the edges of the shade are spaced sufficiently from the window which would allow light leakage around the edges.
Thus, there is a continuing need for a simple and dependable deployable sun screen systems useful with windshields and other automobile windows which fully cover trapezoidal and other non-rectangular windows when deployed and which may be easily stowed out of the way of the vehicle occupants when not in use.